Internet protocol (IP) emergency connections (ITEC) telephony

ABSTRACT

An IP Telephony Emergency Connections (ITEC) system and method that determines the precise origin of an emergency call and routes the call to the proper Public Service Answering Point (PSAP). A source-based routing mechanism is provided in an IP telephony type network, such as a VoIP or IP over LAN/ATM. Emergency calls are routed to the correct PSAP jurisdiction. Each server/switch may include the mechanism such that the IP Telephony network can identify an E911 connection and egress to a public network at a point closest to the emergency call point of origin. Whenever an emergency number call is made, the call&#39;s origin is determined during call setup establishment. Every port or end user jack in the network is assigned a Source Group Index (SGI), which is a number or index representing each PSAP jurisdiction in the network. All ports/jacks within the same PSAP jurisdiction are assigned the same SGI. Users may be in different areas of multiple PSAP jurisdictions.

RELATED APPLICATION

[0001] This application is related to co-owned co-pending applicationSer. No. 09/816,627 entitled “Priority Based Methods and Apparatus ForTransmitting Accurate Emergency Location Identification Numbers (ELINs)From Behind A Multiline Telephone system (MLTS)”; co-owned, co-pendingapplication Ser. No. 09/816,380 entitled “Methods And Apparatus ForTransmitting Over A Private Network Accurate Emergency LocationIdentification Numbers (ELINs) From Behind a Multiline Telephone System(MLTS); co-owned co-pending application Ser. No. 09/816,823 entitled“Methods And Apparatus For Transmitting Accurate Emergency LocationIdentification Numbers (ELINs) From Behind A Multi-Line Telephone System(MLTS) After An Emergency Caller Disconnects”; co-owned co-pendingapplication Ser. No. 09/816,838 entitled “Methods And Apparatus ForTransmitting Accurate Emergency Location Identification Numbers (ELINs)After An Emergency Caller Disconnects”; co-owned co-pending applicationSer. No. 09/815,685 entitled “Methods And Apparatus For Dialing AnEmergency Telephone Number From A Teleworking Client Remotely Coupled ToA PBX”; co-owned co-pending application Ser. No. 09/815,468 entitled“System For Dialing An Emergency Telephone Number From A TeleworkingClient Remotely Coupled To A PBX”; and co-owned co-pending applicationSer. No. 09/816,843 entitled “Methods And Apparatus For TransmittingAccurate Emergency Location Identification Numbers (ELINs) From Behind AMulti-Line Telephone System (MLTS) Utilizing Port Equipment Numbers”,the complete disclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to telecommunications systems, especiallytelecommunication systems capable of computer telephony such as voiceover internet protocol (VoIP). Specifically, the invention relates tocompleting an emergency, e.g. 911, call from a station/device over adata network, e.g., a private corporate local area network (LAN/IP) orthe Internet, to a public network emergency facility and deliveringprecise location information of the caller and a call back number basedon a port equipment number associated with the port from which theemergency call originated.

[0004] 2. Brief Description of the Prior Art

[0005] When a caller calls an emergency number, e.g. 911 (E911), thecall is routed to a Public Safety Answering Point (PSAP). In somejurisdictions, regulatory agencies require that the caller's telephonenumber/callback number and/or precise physical location referred to asan Emergency Location Identification Number (ELIN), be automaticallyprovided to the PSAP. The information in the ELIN is used to locate thecaller and to call back to the caller should there be a disconnect.

[0006] A caller identification (i.e., telephone number and ELIN) may bedelivered to the PSAP either in-band (e.g., using DTMF signaling) orout-of-band (e.g., using ISDN signaling) depending on the type of trunkcircuit employed. Normally, for residential callers Caller ID number issufficient for the PSAP. In some cases, the ELIN is geodetic, i.e.includes earth coordinates or geo-positional synchronous (GPS) data.

[0007] Digitally encoded voice communications that are transmitted overa network, using what is typically referred to as Voice over InternetProtocol (VoIP) may originate anywhere and possibly, follow a circuitousconvoluted route to a distant destination for far-end hop-off to apublic service telephone network (PSTN). Thus, placing an E911 call overa VoIP enabled telephone network, may be a problem. Heretofore, therehas not been a way in an IP network (e.g., voice over IP) to identifythe source location of an originating device whose destination is 911(or other emergency number) and to route the call to the proper PSAPjurisdiction (or other designated destination).

[0008] Thus, there is a need for a way to determine the properdestination PSAP of emergency calls in an IP network and further tocorrectly route an emergency call from the IP network to the publicnetwork of the appropriate PSAP.

SUMMARY OF THE INVENTION

[0009] It is therefore a purpose of the invention to accurately reportthe emergency location of an emergency caller calling on a VoIP networkto public safety personnel.

[0010] It is another purpose of the invention to accurately report thecallback number of an emergency caller using VoIP to public safetypersonnel.

[0011] It is yet another purpose of the invention to accurately reportthe ELIN and callback number of a caller making an emergency call usingVoIP to call a PSAP over a private network in a manner that does notinterfere with features of the PBX/MLTS.

[0012] It is yet another purpose of the invention to locate an E911caller from the source of the call, regardless of the call originationlocation including calls originating in an IP private network, and routethe call to the most appropriate PSAP, closest to the caller.

[0013] The present invention is an IP Telephony Emergency Connections(ITEC) system and method that determines the precise origin of anemergency call and routes the call to the proper Public ServiceAnswering Point (PSAP). A source-based routing mechanism is provided inan IP telephony type network, such as a Voice over IP (VoIP) or IP overLocal Area Network/Asynchronous Transfer Mode (LAN/ATM). Emergency callsare routed to the correct PSAP jurisdiction. Emergency calls mayinclude, but are not limited to voice calls. The routing mechanism maybe deployed in any intelligent distributed or centralized network. Forexample, a server/switch at a gateway may include the mechanism suchthat the IP Telephony network can identify an E911 connection and egressto a public network at a point closest to the emergency call point oforigin. Whenever a call is recognized as being an emergency number call,the call's origin is determined during call setup establishment. Everyport or end user jack in the network is assigned a Source Group Index(SGI), regardless of whether a port is physical or logical, e.g., formulti-drop. An SGI is a number or index representing each PSAPjurisdiction in the network. Port/jack level management granularityallows any server/switch to serve users that may be in different areasof multiple PSAP jurisdictions. So, all ports/jacks within the same PSAPjurisdiction are assigned the same SGI.

[0014] Advantageously, an emergency call made using VoIP is routed tothe proper authorities. The routing can be provided at any networkentity that is equipped with appropriate trunks, including the networkentity where the call originated or, at a gateway located near thesource of the call. This call handling circumvents normal call routingand may fulfill expected governmental requirements for emergency calls.Accordingly, emergency request information is sent to the correct PSAPregardless of where the user resides in an IP network.

[0015] Thus, the apparatus of the invention includes databasemanagement, emergency number detection, call routing and both ISDN andnon-ISDN signaling. The present invention may be configured so thateither the callback number, the ELIN, or both are transmitted to thePSAP. Further, the invention may be configured to recognize multipleemergency numbers and to give emergency calls priority overnon-emergency calls.

[0016] Additional benefits and features of the invention will beapparent from the following detailed description taken together with theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 shows an example of an overview of a preferred embodimentnetwork with Voice over IP (VoIP) emergency call capability (IPTelephony Emergency Connections (ITEC)) according to the presentinvention;

[0018]FIG. 2 shows an example of ITEC components of network elements ofa preferred embodiment system according to the present invention;

[0019]FIG. 3 shows an example of SGI and ELIN index port assignment forthree shelves;

[0020]FIG. 4 shows an example of various network entities distributedthroughout different geographically distinct PSAP jurisdictions withcorresponding routes and trunk group assignments;

[0021] FIGS. 5A-B are a flow diagram showing how emergency numbers areprocessed according to a preferred embodiment of the present invention;

DETAILED DESCRIPTION

[0022] Turning now to the drawings and more particularly FIG. 1 shows anexample of an overview of a preferred embodiment network 100 with Voiceover IP (VoIP) emergency call capability (IP Telephony EmergencyConnections (ITEC)) according to the present invention. Essentially,ITEC is a source-based routing mechanism in an IP Telephony type network(e.g., voice over IP or IP over Local Area Network/Asynchronous TransferMode (LAN/ATM)) that determines the precise emergency call origin in aPublic Service Answering Point (PSAP)) jurisdiction of an emergency call(including, but not limited to voice calls) and routes the call to theappropriate public safety personnel in that jurisdiction. This routingmechanism may be developed in an intelligent network routing entity 102,104 with other network entities 106, 108 that are in communication witheach other over Local Area Network (LAN) or Wide Area Network (WAN) 110.The intelligent network routing entity maybe distributed or centralized,for example, a server/switch, gateway 102, 104, where the IP Telephonynetwork can convert the emergency call connection (if required) andegress to a public network at a point closest to the point of origin ofthe call. Whenever a call is recognized as an emergency number, thepreferred routing mechanism makes a call origin determination duringcall setup establishment. Each server/switch 102 may serve users thatspan multiple PSAP jurisdictions, so every port or end user jack in thenetwork 100, whether physical and/or logical e.g., for multi-drop, isassigned a Source Group Index (SGI). Each PSAP jurisdiction in thenetwork is represented by one SGI and so, all ports/jacks within thesame PSAP jurisdiction are assigned the same SGI.

[0023] All network entities, such as ethernet switches and servers,where users are attached to ports/jacks or where end user devices areattached to the IP network include a unique Emergency ConnectionIdentifier (ECI) module. At least one Network Area Router (NAR) module(in server 102 in this example) provides database maintenance,administration and special messaging, i.e., packets and internalmessages. The ECI modules and data may reside in one or more networkentities.

[0024] For purposes of the description of the present invention, networkentities may be categorized as belonging to one of three categories,NE1, NE2 or NE3. NE1 type devices include only an ECI module and do notinclude a gateway (GWY) or a centralized manager (MGR). NE2 type devicesinclude both an ECI module and a gateway, but do not include acentralized manager. NE3 devices are Network Area Routers (NAR) thateach include an ECI module, a gateway and a centralized manager. Thus,server 102 is an NE3 type network entity. Remote switch 104 is an NE2type network entity. Devices 106, 108 are each NE1 type networkentities.

[0025] Server 102 is shown with ports for fixed stations, wirelessphones, IP devices and one or more remote stations 112 attached and incommunication with the LAN/WAN 110 through network area router 114. Bothgateway 116 and trunks 118 are connected to a public service (orswitched) telephone network (PSTN) 120. Each remote station 112 isdirectly connected to PSTN 120. Remote switch 104 is shown with portsfor IP devices, fixed stations, wireless phones and one or more remotestations 122. As an NE2 device, remote switch 104 includes the LAN/WAN110 through a trunk 124 with the PSTN 120. So, in this example, networkentity 106 is an internet protocol (IP) device, e.g., a communicationdevice with an attached handset 126. Device 108, which is an NE1 typenetwork entity, includes ports for various communication type devicessuch as remote station 128, fixed stations, wireless devices and IPdevices. The PSTN 120 is in telephonic communication with Public SafetyAnswering Point (PSAP) jurisdictions (J1-Jn) that are located in eachcorresponding port location for each of the network entities 102, 104,106, 108.

[0026] Further, the PSTN 120 may be in communication with a remotedial-up Emergency Location identification Number Apparatus as describedin co-owned co-pending application Ser. No. 09/816,627 entitled“Priority Based Methods and Apparatus For Transmitting AccurateEmergency Location Identification Numbers (ELINs) From Behind AMultiline Telephone system (MLTS)”; co-owned, co-pending applicationSer. No. 09/816,380 entitled “Methods And Apparatus For TransmittingOver A Private Network Accurate Emergency Location IdentificationNumbers (ELINs) From Behind a Multiline Telephone System (MLTS);co-owned co-pending application Ser. No. 09/816,823 entitled “MethodsAnd Apparatus For Transmitting Accurate Emergency LocationIdentification Numbers (ELINs) From Behind A Multi-Line Telephone System(MLTS) After An Emergency Caller Disconnects”; co-owned co-pendingapplication Ser. No. 09/816,838 entitled “Methods And Apparatus ForTransmitting Accurate Emergency Location Identification Numbers (ELINs)After An Emergency Caller Disconnects”; co-owned co-pending applicationSer. No. 09/815,685 entitled “Methods And Apparatus For Dialing AnEmergency Telephone Number From A Teleworking Client Remotely Coupled ToA PBX”; co-owned co-pending application Ser. No. 09/815,468 entitled“System For Dialing An Emergency Telephone Number From A TeleworkingClient Remotely Coupled To A PBX”; and co-owned co-pending applicationSer. No. 09/816,843 entitled “Methods And Apparatus For TransmittingAccurate Emergency Location Identification Numbers (ELINs) From Behind AMulti-Line Telephone System (MLTS) Utilizing Port Equipment Numbers”,the complete disclosures of which are hereby incorporated by reference,and referred to generically hereinafter as ELIN references or an ELINapparatus.

[0027] It is understood that the number of PSAPs involved depends on thelocation of ports connecting each individual fixed station, wirelessdevice, IP device and remote station for each of the individual networkentities 102, 104, 106, 108. Each PSAP jurisdiction is a geographicallydistinct location, e.g., a county, a town, a city, a precinct, etc.) Allports/jacks, physically located within each jurisdiction must have thesame SGI assigned for that particular region. Therefore, users may beattached to/move between the different network entities and the assignedSGI is based on the port to which they are physically connected.Emergency calls placed from each user are routed according to the SGI tothe correct PSAP jurisdiction. Users connected to NE1 network entities106, 108 are routed through server 102 or remote switch 104 to the PSTN120 (i.e., whichever entity has access to the PSAP correct jurisdiction)and, thereafter, the call is directed to public safety personnel injurisdiction, J1 . . . , Jn.

[0028] When a number is dialed, the ECI module checks an ECI emergencynumber table to determine if the number is an emergency call number asindicated by whether the dialed number is listed as such. If the dialednumber is not found in the ECI table, the call is not processed by ITEC.However, if the number matches an emergency number in the ECI table,then, the ITEC processes the call and it is routed to a PSAPjurisdiction based on the originating port SGI. The NAR determines theroute based on the port's SGI which is included in routing tables androutes emergency calls to egress to the proper PSAP jurisdiction.Preferably, the ECI modules are located in each individual networkentity 102, 104, 106, 108. However, all ECI modules may be located at acentral processing entity, provided the PENs are unique network wide(e.g., prefixed with a network entity unique identifier).

[0029]FIG. 2 shows an example of ITEC components of network elements ofa preferred embodiment system according to the present invention. Asnoted above, each network element includes an emergency connectionidentifier (ECI) module 150 regardless of network element type. Further,at least one network element includes a network area router NAR 160,i.e., NE3 type network element. The ECI module 150 both sends andreceives messages and handles all communications between the NAR 160 andusers at connected ports, regardless of whether the ECI module 150 andNAR 160 are in the same or separate network elements. Accordingly, theECI module 150 also includes ECI data in an ECI data table 152 for eachport in the network entity. An ECI table 152 entry is attached to anyemergency messages that are sent from or received by the network entity.ECI data table 152 includes a port equipment number (PEN) field, a portsource group index number (SGI) field and a local PSAP emergencylocation identifier number (ELINx) field. Also, the ECI module 150includes an emergency number table 154 with a list of emergency numbersand associated priorities.

[0030] If the network entity is NE3 type, it includes network arearouter 160 and logic 161. The NAR logic 161 routes messages to and fromconnected network entities as directed by each particular networkentity's ECI module 150. Accordingly, the network area router maintainsan ELIN table 162, a source group table 164, an IP packet receive/sendtable 166 and a routing table 168. The routing table 168 correspondsmessages to a particular origination port as identified by the ECI dataof the particular message.

[0031] Each ECI module 150 recognizes emergency calls that originatefrom the particular network entity in which the ECI module 150 resides.The ECI module 150 identifies each emergency call's SGI and otherpertinent information (e.g., ELIN) and flags emergency calls foremergency priority. The ECI module 150 compares each call's destinationdigits to entries in an ECI emergency number table 154. The ECI module150 transmits a small data packet (or internal message when the NAR 160and ECI module 150 reside in the same network entity) that includes theport's SGI, destination digits and other connection information to theNAR 160. The NAR logic 160 processes each data packet (subject to normalretransmission handling) or internal message (if the ECI module 150 andNAR 160 are located together) in order to determine how the call shouldbe switched. A call may be sent initially as data packets for partialpacket switching and, then to a gateway for circuit-switching or,immediately to a local B-channel for circuit switching from the sourceentity. The routing instructions are returned to the sender ECI module150 or an acknowledgment (ACK) may be sent when another gateway is toroute the call. This message/packet exchange must be uniquely identifiedwith each particular call.

[0032]FIG. 3 shows an example of SGI and ELIN index port assignments forthree shelves 170, 172, 174. Each shelf 170, 172, 174 includes two slotsindicated by a corresponding 1 or 2 subscript, e.g., 170 ₁, 170 ₂.Boards in each slot may be stations/lines, trunks or IP interfaces, forexample. Ports 176, 178, 180, 182, 184 are shown, typically in eachslot, e.g., on station/lines 170 ₁, 170 ₂ and so on. It should be notedthat this is for example only and the present invention may be appliedto any combination of slots or shelves. TABLE 1 PEN SGI ELIN indexComment 1-1-001 2 101 fixed station 1-2-005 2 220 IP device 1-3-001 8125 RS 1-4-002 2 23 wireless phone

[0033] Table 1 is an example of an ECI PEN table, e.g., table 152 ofFIG. 2. Port Equipment Numbers (PEN) point to the assigned ELIN and SGIfor the particular port, where the port is ambiguous network wide. Portequipment numbers are assigned to each port and have the format: shelfnumber—slot number—port number. Thus, the number 2-11-111 indicatesshelf number 2, slot number 11, port number 111. Typically fixedstations are in the same PSAP jurisdiction as the particular networkentity and so, have the same SGI. If a station/device or RS extends intoanother PSAP jurisdiction, a different SGI index (i.e., the SGI fordevices in that jurisdiction) is assigned. The ELIN index is asdescribed in the ELIN references. TABLE 2 Dialed # Priority 9 1 1 1 9 91 1 1 9 9 3 1 1 1 1 3 e.g., local police station

[0034] Table 2 is an example of an ECI Emergency Number Table. Calls areassigned priority relative to normal everyday calls which may be given alowest priority, e.g., priority 9. Emergency calls are typically givenhighest priority, priority one. So, for purposes of this example, one isthe highest priority and nine is the lowest. Each call is assigned aunique call ID, e.g. a number generated from a random number generator.Any emergency number is flagged by the ECI data and does not include arouting number. When a call is made from a device at a network entity,the ECI module checks against an emergency number in the routing table.If the dialed number is an emergency number, then the ECI moduleprocesses the number. Otherwise the ECI module ignores the number and itis treated as a normal call.

[0035] In this example, shelf 170 has three ports assigned for fixedtelephone, and additional ports are assigned for roaming connection,e.g., cellular phones. A remote station may also be connected tostation/line boards 1701, 1702. Fixed telephone 186 is assigned to SG1and is located in a different PSAP jurisdiction than fixed telephone188, which is assigned to SG4. Trunks in shelf 172 connect to a PSTN andalso provide private and wireless connections to the PSTN. The firstport of shelf 172 is also shown in the same jurisdiction as fixedtelephone 186 and so, is also assigned SG1. Shelf 174 is shown with portconnections to a LAN. Each of the LAN port connections may bedistributed in different jurisdictions and assigned, SG1, SG2, SG3 . . ., for example. An ECI message may be internal (when the ECI module islocated on an NE3 type network entity) or over a signaling channel to anNE3 type network entity. Generally, an ECI packet includes an ECI packettype, a calling number (i.e., the user not the port number) a callednumber (the PSAP telephone number) a network-wide unique call ID and ECIdata. As noted above ECI data may include the SGI and ELIN index.Optionally, a priority may also be included.

[0036]FIG. 4 shows an example of various network entities distributedthroughout different geographically distinct PSAP jurisdictions withcorresponding routes and trunk group assignments. This example includesten individual network entities 192-210. Network entities 192, 194, 196and 198 are NE1 type network entities. Network entities 200, 202, 204,and 206 are NE2 type network entities. Network entities 208 and 210 areNE3 type network entities. For redundancy, multiple NE3 type networkentities (2 in this example) may serve NE1 and NE2 type networkentities. A remote station 212 and a mobile/wireless phone 214 areshown. These ten network entities 192-210 include ports that aredistributed in ten individual PSAP jurisdictions designated J1-J10.Typically, network entities have ports in the PSAP jurisdiction in whichthey are located. However, network entity 200 also includes ports in twoother jurisdictions, including jurisdiction J2, J8 and J10. Networkentity 206 includes ports in jurisdictions J6 and J7. Mobile phone 214is potentially in connection with each of network entities 198 and 202and 210 because of its roaming capability, e.g., handoff from onenetwork entity 198, 202, 210 to another. Therefore, mobile phone 214 maybe in each of jurisdictions J3, J9 and J4, respectively.

[0037] Accordingly, an emergency call may be made from a network port onnetwork entity 200 where the port resides in jurisdiction J10. Relevantcall information is passed over the IP network to one of NE3 208 or 210,depending upon which is controlling NE2 200 at the time of the call. Anemergency call from device 197 is signaled through NE2 200 which hasaccess to PSAP J10. The emergency call is relayed to the PSAPjurisdiction in J10. Likewise an emergency call made from network entity194 in jurisdiction J1 is passed to network entity 208 which is anetwork area router. Network area router 208 passes the call to the PSTNto make the connection to the PSAP in J1. Also, an emergency call madefrom network entity 192 in jurisdiction J7 is signaled through networkarea router 208 to take route 17 from network entity 206 where the callis made, i.e., to the PSAP jurisdiction in J7.

[0038] So, for every PSAP jurisdiction where users reside in the IPnetwork, at least one gateway (capable of switching a connection betweenIP network and PSTN technology, CAMA or ISDN) also must exist withinthat area. This gateway serves calls originating in that PSAP by eitherrouting local calls to the PSTN or converting arriving emergency callsfrom IP packets to circuit-switched technology for egress to the publicnetwork. TABLE 4 Dial Pattern Rt # Priority Comments 1 2 3 4 Rt 55 9normal call 9 1 1 Go to SG Table ECI data ITEC call 9 9 1 1 Go to SGTable ECI data ITEC call 9 9 3 1 1 1 1 Go to SG Table ECI data ITEC call

[0039] Table 4 is an example of a NAR routing table with emergency callnumber entry examples. Each call number entry in this example includes adial pattern, ECI data (SGI priority), a route number and a prioritynumber. In this example a first dial pattern 1234 represents any DIDnumber, for example, and the ECI data field indicates that the number isnot an emergency number. This first dial pattern is associated with aroute number 55 and given a low priority, 9, in this example. Thefollowing three entries are examples of emergency numbers. If anemergency number is dialed and matches one of these three the dialpatterns, then, the corresponding ECI data indicates that the entry isan emergency number and must be handled by the ECI module. A typicalUnited States emergency number, 911, is the second entry in the routingtable. It is understood that any number may be selected as an emergencydial number. A corresponding ECI data entry for this second dial patternmay be a Y, indicating yes. The following dial pattern entry is 9911corresponding to dialing 911 externally to a PBX, e.g., dialing 9 for anexternal line followed by 911. The final dial pattern entry is 999,which is also shown as in this example as corresponding to an emergencynumber and may include a Y in the corresponding ECI data field. TABLE 5Index Rt # Comment 0 . Reserved . . 1 15 2 13 Mobile, Station, IP call911 from NE 2, PSAP J2 . . . . . . 8 14 RS called 993111 (local police),PSAP J8 . . .

[0040] Table 5 shows an example of a Source Group Table with referenceto the configuration and topology of the example of FIG. 4 thatcorresponds each source group index with a route number. In thisexample, source group index 0 is reserved for IP devices that are notdirectly connected to a network entity of the private IP network. Theseindirectly connected IP devices cannot ordinarily be located by aPEN-SGI-ELINx and so, in this example, they signal location informationto a NE3 type network entity as SG0. This signaling may be by using apre-programmed speed dial key or by providing GPS information, forexample. Either type of signaling requires that the received informationbe processed to extract the correct call routing to the appropriatePSAP. Typically, can ELIN is not available from indirectly connected IPdevices and so, inclusion of a callback number in the signaling isessential. Source group index 2 indicates that a emergency call has beenplaced from a geographical location served by route number 13 and, asindicated by the corresponding comments, that the call is an emergencycall from a station in PSAP jurisdiction J2, e.g., a mobile phone, alocal phone or a local IP phone. TABLE 6 Index ELIN TYPE Callback #Other table elements 0 1002001000 1 5619235000 N/A 1 1002001001 99547301000 N/A 2 1002001002 9 calling party # N/A . . .

[0041] Table 6 is an example of an ELIN index table as described in theELIN references and is shown for example only.

[0042] FIGS. 5A-B show a flow diagram of how emergency numbers areprocessed according to the preferred embodiment of the presentinvention. In step 212, a user dials a number that is checked againstlisted emergency numbers 214 to determine if it is an emergency number.If not, processing continues as normal in 216. Otherwise, the number is:an emergency number at one of a fixed station connected to a networkentity 218; at a network entity dialed directly connected to the network220; at a wireless or mobile phone in communication with a networkentity 222 using for example time division multiplex (TDM); or, at aremote station or switch 224 in communication with a network entity.Upon receiving the number, the particular ECI module identifies theoriginating port in a respective one of step 226, 228, 230, or 232. So,for each connected port, the PEN, ELIN index, and the corresponding SGInumber are identified. If the originating port is connected directly tothe network and not to a network entity, then this is noted in step 236and processing depends upon whether the device provides the selectedindirect device SGI (e.g., SG0), appropriate callback number andavailable location data (e.g., GPS). Otherwise, however, at this pointemergency calls that originate from a port connected to a network entityother than a network area router (i.e., an NE3 type network entity) arerouted by a network area router according to source group number andELINx, if available.

[0043] So, the call is checked in step 238 to determine whether itoriginates at a network area router or originates at an NE1 or NE2 typeof network entity. If the call originates at a network area router port,then, in step 240 the call generates an internal message and is treatedas such in step 242 and passed to the network area router in step 244.If, however, in step 238 it is determined that the call originates froman NE1 or NE2 type network entity, then, in step 246 the message isencoded as an IP packet with data link control, and transported via theIP physical layer. In step 248 a network wide unique call ID is assignedto the IP message, which includes the ECI data, and is sent as anemergency call request packet to the network address router. In step 250the packet is received and passed to the network area router in step244. In step 252 the called number is matched with a digit pattern inthe routing table. In step 254 if the call is not associated with anECI, it is treated as a normal call. Otherwise, it is treated as anemergency call.

[0044] Otherwise, in step 258 the ECI index is retrieved from the sourcegroup table. In step 260 the call back number and ELIN number areretrieved from the ELIN table. In step 261 an acknowledgment packet issent to the ECI module in the originating network entity. Next, in step262 a check determines if the source group number corresponds to a PSAPjurisdiction as a local to the network area router. If the PSAPjurisdiction is local to the network area router, then, in step 264 thecall is queued according to priority number. In step 266, the queuedcall is placed to the local PSAP. So, a connection is made to theemergency number at the local PSAP jurisdiction and, the ELIN call backnumber is passed, for example over an ISDN network, to the local PSAPjurisdiction. If however, in step 262 it is determined that the PSAPjurisdiction is not local to the router, then in step 270, an NE2 or NE3type network entity that is local to the emergency call source isidentified and, the network area router sends the packet to theidentified NE2 or NE3 type network entity.

[0045] According to the present invention in the context of theaforementioned examples, the call may be routed directly to the publicnetwork or, first transit over the private network (via one or moreother MLTS) to a far end “hop off” to the public network. The privatenetwork route may include ISDN (e.g., QSIG/PSS1) or analog tie trunks.

[0046] Furthermore, according to the invention, the ELIN/callback numberis sent with each emergency call over the private network, and then, toa public gateway multi line telephone system (MLTS). Dual ToneMulti-Frequency (DTMF) signals are encoded and passed over analog tieand facility IE Application Data Protocol Units (APDU) and areimplementation dependent private extensions on a private network. TheMLTS may send the emergency call and ELIN/callback number via an ISDNPRI or an analog Centralized Automatic Message Accounting (CAMA) trunkto the public network. In either case, the Central Office receives thenecessary information and routes each emergency call to the proper 911Tandem Office which routes the call to the appropriate PSAP.

[0047] While the invention has been described in terms of preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

What is claimed is:
 1. A method for processing an emergency call madefrom a device connected to a network entity on a private network, saidprivate network including one or more network entities, said methodcomprising the steps of: a) assigning a source group index (SGI) to eachnetwork entity port; b) identifying emergency calls; c) determining anorigination port for each identified port emergency call; d) identifyinga public safety answering point (PSAP) jurisdiction corresponding to theSGI assigned to each determined origination port; and e) connecting eachidentified emergency call with a corresponding identified PSAP.
 2. Amethod as in claim 1 wherein said emergency call is a Voice overInternet Protocol (VoIP) call and the step (b) of identifying emergencycalls comprises the steps of: i) comparing a dialed number for each callwith known emergency numbers; and ii) sending an emergency connectionidentifier (ECI) packet to a network area router (NAR) for a dialednumber matching a known emergency number.
 3. A method as in claim 2wherein the ECI message includes an ECI packet type, a calling number, acalled number, a call ID number and ECI data.
 4. A method according toclaim 3 wherein the ECI data includes the SGI assigned to saidorigination port of said identified emergency call and an emergencylocation identification number (ELIN) index number.
 5. A method as inclaim 4 wherein the ECI packet further includes call priority.
 6. Amethod as in claim 5 wherein call priority is determined in the step (i)of comparing the dialed number with known emergency numbers.
 7. A methodas in claim 6 wherein identified emergency calls are queued according tosaid call priority.
 8. A method as in claim 4 wherein the PSAPjurisdiction is identified by a route number retrieved from a sourcegroup table and corresponding to said SGI assigned to said identifiedemergency call.
 9. A method as in claim 8 wherein the route numbercorresponds to the identified emergency call to said PSAP jurisdiction.10. A method as in claim 9 further comprising the step of: (f) sendingan acknowledgment from said NAR to an ECI module located at saidorigination port.
 11. A network including an apparatus for processingemergency calls made from connected devices, said network comprising: aplurality of network entities communicating with each other; a pluralityof devices connected to said network entities, at least one networkentity having two or more connected said devices; a network area router(NAR) in at least one network entity; and an emergency connectionidentifier (ECI) module in at least one network entity with one or moreports, said ECI module in communication with said NAR, said ECI moduleidentifying emergency calls made from devices connected to said one ormore ports and forwarding identified emergency calls to said NAR, saidNAR identifying a public safety access point (PSAP) corresponding to apoint of origin of each identified emergency call and forwarding saideach identified emergency call to said PSAP.
 12. A network as in claim11 wherein said ECI module comprises: an emergency number tableincluding one or more series of dialed numbers corresponding toemergency telephone numbers; and an ECI port equipment number (PEN)table including port equipment numbers for ports located in said networkentity in which said ECI module is located and corresponding each saidPEN with a source group index (SGI) number, said SGI numbercorresponding to a PSAP jurisdiction.
 13. A network as in claim 12wherein the ECI emergency number table further includes priority numberscorresponding to said emergency numbers.
 14. A network as in claim 13wherein said ECI PEN table further includes an ELIN index correspondingto each PEN entry.
 15. A network as in claim 12 wherein the NAR includesa routing table, a source group table and an ELIN table.
 16. A networkas in claim 15 wherein said routing table provides a routing foridentified dialed emergency numbers.
 17. A network as in claim 16wherein the source group table indicates a route number for each SGInumber.
 18. A network as in claim 12 wherein said at least one ECImodule is two or more ECI modules, at least one of said two or more ECImodules is located on a common network entity with said NAR.
 19. Anetwork as in claim 18 wherein at least one network entity includesports located in two or more PSAP jurisdictions.
 20. A network as inclaim 18 wherein said common network entity includes a gateway incommunication with a public service telephone network (PSTN).
 21. Anetwork as in claim 20 wherein at least one other of said plurality ofnetwork entities includes an ECI module and a gateway in communicationwith said PSTN.